by Donna Leinwand Leger, USA TODAY

by Donna Leinwand Leger, USA TODAY

A series of freeway shootings Tuesday in Orange County, Calif., has left four people dead, including the suspect, and three people injured, the Tustin Police Department said.

Police are still trying to confirm how the shootings are connected, but spokeswoman Gail Krause told USA TODAY the killing spree started in Ladera Ranch before the suspect moved north along the freeway to Tustin.

Tustin Police Chief Scott Jordan identified the gunman as Ali Syed, a 20-year-old unemployed part-time student, who lived in the Ladera Ranch home where the first victim, a woman, was killed.

The shootings began shortly before 4:45 a.m. when deputies responding to a call found the body of a dead female shot multiple times in a house in Ladera Ranch.

At 5:10 a.m., police in Tustin received a call about a man with a gun at a major intersection, police spokesman Lt. Paul Garaven said. Syed had attempted to steal a car, Garaven said. When the car's owner drove off, Syed shot and wounded him, he said.

Syed then crossed the street to a gas station where he carjacked a pickup truck. This time, Garaven said, "no rounds were fired. He just took the car and fled."

Several minutes later, police received another report of a car jacking in Santa Ana. Syed had ordered the victim out of the car, walked him to the median strip and shot him in the back, killing him, Garaven said.

The gunman then drove two miles south where he killed a third victim and shot another person in the arm, he said. This time, Syed stole a white utility vehicle. Witnesses called in sightings to the California Highway Patrol, which spotted and began following the vehicle, Garaven said. At 5:50 a.m., Garaven said, the vehicle slowed, Syed exited and then shot himself in the head.

Throughout the hour-long ordeal, Syed apparently shot at others on the highway, Garaven said. At least three people reported that the suspect shot at their cars, including one person with minor injuries, he said.

Investigators are searching for a motive, Garaven said. Syed had no criminal record, he said. The gun, a 12-gauge shotgun, is no registered to him and had been purchased more than a year ago at a sporting goods store, he said. Federal authorities are tracing the gun, he said.

"I do not believe any of the victims are related to each other. It might have been a random thing," Orange County sheriff's spokesman Jim Amormino told KNBC-TV.. "We just don't know."